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From: Luiz Capitulino <lcapitulino@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Chris Metcalf <cmetcalf@mellanox.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Christoph Lameter <cl@linux.com>,
	"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
	Wanpeng Li <kernellwp@gmail.com>, Mike Galbraith <efault@gmx.de>,
	Rik van Riel <riel@redhat.com>
Subject: Re: [GIT PULL] isolation: 1Hz residual tick offloading v4
Date: Mon, 29 Jan 2018 11:27:34 -0500	[thread overview]
Message-ID: <20180129112734.27553e0e@redhat.com> (raw)
In-Reply-To: <20180129155431.GW2269@hirez.programming.kicks-ass.net>

On Mon, 29 Jan 2018 16:54:31 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> On Mon, Jan 29, 2018 at 10:33:16AM -0500, Luiz Capitulino wrote:
> > Cool, passing tsc=reliable worked for me. I finally got to the tick to
> > go completely away. While I agree that fixing that is beyond the scope
> > of this series, I think we should improve it anyway since it will probably
> > come up for people trying the new nohz_full=.  
> 
> The only way to fix that is to audit all BIOS code :/ Short of that, we
> need to periodically test the TSC on each CPU/SOCKET to verify its still
> in step with expectation.

Oh, OK. I thought we could find a way to avoid the timer in the kernel
for certain CPUs like mine.

Thanks for the explanation.

> 
> Sadly MSR_IA32_TSC and MSR_IA32_TSC_ADJUST are writable registers and
> BIOS monkeys occasionally write to them for 'raisins-of-insanity'.
> 

  reply	other threads:[~2018-01-29 16:27 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-19  0:02 [GIT PULL] isolation: 1Hz residual tick offloading v4 Frederic Weisbecker
2018-01-19  0:02 ` [PATCH 1/6] sched: Rename init_rq_hrtick to hrtick_rq_init Frederic Weisbecker
2018-01-19  0:02 ` [PATCH 2/6] nohz: Allow to check if remote CPU tick is stopped Frederic Weisbecker
2018-01-19  0:02 ` [PATCH 3/6] sched/isolation: Isolate workqueues when "nohz_full=" is set Frederic Weisbecker
2018-01-19  0:02 ` [PATCH 4/6] sched/isolation: Residual 1Hz scheduler tick offload Frederic Weisbecker
2018-01-29 15:38   ` Peter Zijlstra
2018-01-29 16:48     ` Frederic Weisbecker
2018-01-29 17:20       ` Peter Zijlstra
2018-01-29 15:39   ` Peter Zijlstra
2018-01-19  0:02 ` [PATCH 5/6] sched/nohz: Remove the 1 Hz tick code Frederic Weisbecker
2018-01-19  0:02 ` [PATCH 6/6] sched/isolation: Tick offload documentation Frederic Weisbecker
2018-01-24 15:46 ` [GIT PULL] isolation: 1Hz residual tick offloading v4 Luiz Capitulino
2018-01-29  1:10   ` Frederic Weisbecker
2018-01-29 15:33     ` Luiz Capitulino
2018-01-29 15:54       ` Peter Zijlstra
2018-01-29 16:27         ` Luiz Capitulino [this message]
2018-01-29 15:47     ` Peter Zijlstra
2018-05-22 19:10     ` Yauheni Kaliuta
2018-05-25  2:56       ` Frederic Weisbecker
2018-05-25 12:51         ` Luiz Capitulino
2018-01-29  1:18 ` (Ping?) " Frederic Weisbecker

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